The thermoplastic properties of a mildly preoxidized Lower Kittanning seam low volatile coal have been examined at elevated pressures of H 2 and He utilizing a high-pressure microdilatometer. It was observed that the ...
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The thermoplastic properties of a mildly preoxidized Lower Kittanning seam low volatile coal have been examined at elevated pressures of H 2 and He utilizing a high-pressure microdilatometer. It was observed that the maximum swelling parameter ( V s , vol%) of the preoxidized coal was significantly restored at elevated pressures of He. The thermoplastic properties of the preoxidized coal were even further restored at high pressures of H 2 . The results indicate that carbonization of this coal at elevated H 2 pressures reduces the effect of preoxidation by removing some of the oxygen introduced during preoxidation and replacing it with reactive donatable hydrogen. It was shown that subsequent heat-treatment of the preoxidized coal at a relatively mild condition (in vacuum at 403 K) results in dramatic reductions in the thermoplastic behaviour of coal when subsequently carbonized at elevated pressures of H 2 or He.
This communication discusses the subject of the relative reactivities of low-rank and bituminous coals in liquefaction. Accounts given by several researchers have provided seemingly contradictory results. An explanati...
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This communication discusses the subject of the relative reactivities of low-rank and bituminous coals in liquefaction. Accounts given by several researchers have provided seemingly contradictory results. An explanation is presented to reconcile these opposing views.
The rapid development of consumer electronic and electric vehicle markets causes the increasing demand for advanced rechargeable ***(Li)metal batteries(LMBs)have attracted considerable attention in recent years due to...
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The rapid development of consumer electronic and electric vehicle markets causes the increasing demand for advanced rechargeable ***(Li)metal batteries(LMBs)have attracted considerable attention in recent years due to their high energy density[1],since the metallic Li anode exhibits the ultra-high theoretical capacity and the lowest electrode potential among various alkali metals[2].
Diamond-like carbon (DLC) exhibits excellent wear and friction characteristics. Transmission electron microscopy (TEM) has been used to investigate the substructures of as-deposited DLC and DLC debris after wear testi...
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Diamond-like carbon (DLC) exhibits excellent wear and friction characteristics. Transmission electron microscopy (TEM) has been used to investigate the substructures of as-deposited DLC and DLC debris after wear testing. The as-deposited DLC was found to consist of a dense, three-dimensional network structure with a medium range order (< 3 nm) present. Diffraction pattern analysis showed that DLC was mainly amorphous. Two diffuse diffraction rings with d(111) = 0.21 nm and d(220) = 0.12 nm were observed, suggesting the presence of a short-range cubic diamond structure (sp(3)). Morphologically, the wear debris was found to be a discontinuous segregation of carbon particles ranging from nano- to micro-size. Diffraction pattern analysis showed that the debris consisted of graphite (sp(2)) and distorted DLC (sp(3)). A wear mechanism has been proposed based on the transformation of DLC to graphite. The transformation is related to the frictional energy and includes two stages: hydrogen release from the structure causing lattice relaxation and shear deformation of the DLC structure producing graphite.
Topology can manifest itself in colloids when quantified by invariants like Euler characteristics of nonzero-genus colloidal surfaces, albeit spherical colloidal particles are most often studied, and colloidal particl...
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We report the characterization of serf-assembled epitaxially grown FeSi2 nanowires （NWs） in terms of electrical and magnetic properties. NWs grown by reactive deposition epitaxy （RDE） on silicon （110） show dimen...
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We report the characterization of serf-assembled epitaxially grown FeSi2 nanowires （NWs） in terms of electrical and magnetic properties. NWs grown by reactive deposition epitaxy （RDE） on silicon （110） show dimensions of lOnmxSnm, and several micrometres in length. By using conductive-AFM （e-AFM）, electron transport properties of one single NW is measured, resistivity of a single crystalline FeSi2 NW is estimated to be 225 μΩ.cm. Using superconducting quantum interference device （SQUID）, we measure a magnetic moment of 0.3 ± 0.1 Bohr magneton per iron atom for these FeSi2 NWs.
A new class of high-entropy M3B4 borides of the Ta_(3)B_(4)-prototyped orthorhombic structure has been synthesized in the bulk form for the first *** with compositions of(V0.2Cr0.2Nb0.2Mo0.2Ta0.2)3B4 and(V0.2Cr0.2Nb0....
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A new class of high-entropy M3B4 borides of the Ta_(3)B_(4)-prototyped orthorhombic structure has been synthesized in the bulk form for the first *** with compositions of(V0.2Cr0.2Nb0.2Mo0.2Ta0.2)3B4 and(V0.2Cr0.2Nb0.2Ta0.2W0.2)_(3)B_(4) were fabricated via reactive spark plasma sintering of high-energy-ball-milled elemental boron and metal *** sintered specimens were〜98.7%in relative densities with virtually no oxide contamination,albeit the presence of minor(4-5 vol%)secondary high-entropy M5B6 *** that Mo_(3)B_(4) or W_(3)B_(4) are not stable phase,20%of M03B4 and W3B4 can be stabilized into the high-entropy M3B4 *** hardness was measured to be 18.6 and 19.8 GPa at a standard load of 9.8 *** work has further expanded the family of different structures of high-entropy ceramics reported to date.
作者：
FRENKLACH, MFuel Science Program
Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802
The factors affecting the formation and growth of polycyclic aromatic hydrocarbons (PAHs) in chlorine-containing environments are investigated. The experimental results obtained in shock-tube pyrol-ysis of chlorinated...
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The factors affecting the formation and growth of polycyclic aromatic hydrocarbons (PAHs) in chlorine-containing environments are investigated. The experimental results obtained in shock-tube pyrol-ysis of chlorinated C1, and C2, hydrocarbons are re-analyzed in terms of Cl-to-H molar ratio of the mixture and it is found that the sooting tendency and hence PAH production are increased with the increase in [C1]/[H] ratio. Based on the analysis of the reaction kinetics and results or detailed modeling, two basic factors are suggested to be responsible for this phenomenon: (1) the enhanced, chlorine-catalized molecular degradation that promotes the formation of aromatic-ring compounds; and (2) the large concentration of CI atoms that accelerates the abstraction of aromatic H from stable PAH molecules, which activates them for further growth. The modeling results also provide an evidence against existence of a correlation between PAHs and CO in flame environments.
In a previous paper we illustrated a Monte Carlo method to calculate the incremental chemical potential between polymer chains of length nu and nu + 1 at all densities. In this document we present a statistical mechan...
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In a previous paper we illustrated a Monte Carlo method to calculate the incremental chemical potential between polymer chains of length nu and nu + 1 at all densities. In this document we present a statistical mechanics model that allows for its quantitative evaluation as a function of chain length and temperature for macromolecular systems at zero density. Through this approach the incremental chemical potential at zero density is shown to be a strong function of chain length at low temperatures, but becomes chain length independent even for short chains (nu greater-than-or-equal-to 3) at higher temperatures. The temperature where the chemical potential becomes essentially chain length independent is a definition of the Boyle transition for finite chain length polymers, and we show that this transition temperature has a well defined chain length dependence. Chain dimensions and incremental entropies associated with chain segments are also found to decrease significantly when the temperature is reduced below this theta-temperature thus providing that chain segments are localized in the vicinity of other segments in the collapsed state. The consequences of these results on the modeling of the phase equilibria of polymer solutions are also examined.
We fabricated sulfur and nitrogen codoped cyanoethyl cellulose-derived carbons(SNCCs)with state-of-the-art electrochemical performance for potassium ion battery(PIB)and potassium ion capacitor(PIC)*** 0.2,0.5,1,2,5,an...
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We fabricated sulfur and nitrogen codoped cyanoethyl cellulose-derived carbons(SNCCs)with state-of-the-art electrochemical performance for potassium ion battery(PIB)and potassium ion capacitor(PIC)*** 0.2,0.5,1,2,5,and 10 A g−1,the SNCC shows reversible capacities of 369,328,249,208,150,and 121 mA h g−1,*** to a high packing density of 1.01 g cm^(−3),the volumetric capacities are also uniquely favorable,being 373,331,251,210,151,and 122 mA h cm^(−3)at these currents,*** also shows promising initial Coulombic efficiency of 69.0%and extended cycling stability with 99.8%capacity retention after 1000 *** proof of principle,an SNCC-based PIC is fabricated and tested,achieving 94.3Wh kg^(−1)at 237.5Wkg^(−1)and sustaining over 6000 cycles at 30 A g−1 with 84.5%*** internal structure of S and N codoped SNCC is based on highly dilated and defective graphene sheets arranged into nanometer-scale *** a baseline S-free carbon for comparison(termed NCC),the role of S doping and the resultant dilated structure was *** to galvanostatic intermittent titration technique and electrochemical impedance spectroscopy analyses,as well as COMSOL simulations,this structure promotes rapid solid-state diffusion of potassium ions and a solid electrolyte interphase that is stable during cycling.X-ray diffraction was used to probe the ion storage mechanisms in SNCC,establishing the role of reversible potassium intercalation and the presence of KC36,KC24,and KC8 phases at low voltages.
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